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With at least a dozen pet-specific apps available in the iTunes store and hundreds of thousands of downloads, apps for pets are exploding, The Wall Street Journal said -- noting that tigers, frogs and even penguins have played them as well.

In the game “Catzilla,” a digital cat can wreck an animated urban landscape. In the “Cat Fishing” app, which has been downloaded half a million times, frisky felines hunt for animated fish; touching the screen is equivalent to dipping their paws in a pond of water. In a sequel (yep, "Cat Fishing 2"), the app meows if the animal loses interest.

And penguins seem to love “Game for Cats,” pecking vigorously at an iPad screen, said Dudley Wigdahl, curator of mammals and birds at the Aquarium of the Pacific in California.

"They got a lot out of it," he told The Journal.. "I didn't expect that."

Some dismiss the apps as a silly fad, well others say it isn’t fair to, say, make a cat endlessly chase a digital mouse it can never catch.

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App developers dismiss such criticisms as, well, catty, The Journal said.

“[People] have negative connotations of a zombie child staring at a TV for hours and hours," T.J. Fuller, who helped develop the popular "Game for Cats," told the paper. "But I think it's quite different for cats," he said, noting that such games challenge cats physically and mentally.

"I started off really early on thinking that it was ridiculous, but it ended up being something really meaningful for people," said Nate Murray, who developed “Game for Cats” with Fuller.

Read more about apps for pets at The Wall Street Journal.